ci: run fmt-clippy-docs on stable

Avoids components sometimes not being available on nightly, and has less complexity than running beta.

Author: Fishrock123

.github/workflows/ci.yaml

@@ -53,11 +53,6 @@ jobs:
     steps:
     - uses: actions/checkout@master
 
-   - name: nightly setup
-      run: |
-        rustup toolchain install nightly
-        rustup default nightly
-
     - name: clippy
       run: cargo clippy --workspace --benches --bins --examples --tests --features "hyperium_http,unstable" -- -D warnings